Spatial variation of heavy metal contamination in roadside soil from hilly terrain of the north-western Himalaya

Fuel-based vehicular emission has been recognised as a potential contributor to the declining air quality and heavy metal contamination of soils. The present study investigated heavy metal contamination in roadside soil along national highway (NH)-21 and a link road in hilly terrain of the Kullu district, northwestern Himalaya, India. The soil samples were analysed for pH, EC and heavy metals, viz., Zn, Fe, Mn, Cu, Pb, Ar and Cr. The heavy metal concentrations were evaluated as per the guidelines provided by competent authorities. The spatial distribution of heavy metal contaminants was depicted in maps using the GIS platform. The pH of the soil was slightly acidic to neutral. The reference sites from the rural area represent the lower heavy metals contamination comparison to the locations along the highway. The heavy metal concentrations decreased with the increasing distance from the edge of the road, while their distribution and mobility were influenced by natural as well human-induced sources. The present study provides the baseline data to optimise the scale of sampling in the hilly terrains that is capable of capturing the effect of the diffuse source for efficient pollution abatement strategies.